If a context has not been assigned or assignment failed, pq may be NULL.
Move the unregister within the protection of the null check.
Reviewed-by: NDean Luick <dean.luick@intel.com>
Signed-off-by: NIra Weiny <ira.weiny@intel.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>